Image processing method, recorder, ink jet recorder, printer driver, image processor, imaging system and imaging method

ABSTRACT

In an ink-jet printing device which has an ink-jet recording head in which a plurality of nozzles are formed, and forms an image based on multi-level image data, a gamma correction parameter is selected according to discharging characteristics of the recording head to an input gradation level or according to lightness characteristics of a printed image to an input gradation level, and an image is formed based on the selected gamma correction parameter. For example, even when there is a variation in lightness characteristics of recording heads as in  FIG. 9 , an optimal gamma correction parameter is selected for each recording head and the image is formed. Thus, a constant image quality is obtained even if the recording heads are exchanged.

TECHNICAL FIELD

The present invention relates to the image-processing method, theprinting device, the ink-jet printing device, the printer driver, theimage processing apparatus, the image forming system, and the imageforming method. More particularly, the present invention relates to theimage-processing method which can correct the variation in eachrecording head without changing the driving conditions of the recordinghead in which gradation printing is possible as in the ink-jet recordinghead or the thermal recording head, the printing device, the ink-jetprinting device, the printer driver, the image processing apparatus, theimage forming system, and the image forming method.

BACKGROUND ART

The printing method in which the printing elements in the recording headin which the plurality of printing elements are provided are drivenbased on the multi-level image data so that an image is formed on therecording medium is known as the ink-jet printing method, the thermalprinting method, etc.

The ink-jet printing method attracts the attention as the office use orothers for the reasons that it enables high-speed printing, it canrecord the image having the gradation levels without requiring anyspecial fixing processing to the plain paper, and the noise occurring atthe time of printing is almost negligible.

Conventionally, various ink-jet printing methods have been proposed andthe products have been produced and used practically.

In this ink-jet printing method, the ink-jet recording head in which theink liquid chamber and the nozzle open to the ink liquid chamber areformed is used, and the pressure is applied to the ink in the ink liquidchamber according to image information, so that a small drop of the inkis discharged from the nozzle and made to adhere to the recordingmedium, such as the paper or the film, and the image is formed on therecording medium.

Moreover, the ink-jet recording head may be classified by thecomposition into the serial ink jet printer type and the line ink jetprinter type.

In the serial ink jet printer, the ink-jet recording head forms thescanning line while scanning the paper in the width direction of thepaper (main scanning), the paper is conveyed after one or more scans arecompleted, and the following scanning line is formed.

On the other hand, in the line serial printer, the nozzles are formed inthe width direction of the paper to cover the whole width of the paper,and the printing is performed by conveying the paper without scanning itin the width direction.

The line ink jet printer is advantageous in that it forms one scanningline in the width direction at a time and the printing speed is high.However, there are the problems in that since the recording head itselfbecomes large, the whole printer must be large in size, and, when theprinting with a high resolution is needed, the arrangement of thenozzles must be made to a high density and the manufacture cost of theink-jet recording head becomes high.

In contrast, the serial ink-jet printer is advantageous in that theimage is formed using the comparatively small recording head, and thedevice cost is low. For this reason, in recent years, many serial inkjet printers have been put in practical use.

The method of applying the pressure to the ink in the ink liquid chamberof the ink-jet recording head may be classified into the method usingthe piezoelectric element (PZT) which is the electro-mechanicaltransducer, and the method using the heat produced in the heatingresistor like the thermal ink jet printer.

The ink-jet recording head is the integrated device which has the nozzledensity in the range of 150-600 dpi and has the number of the nozzles inthe order of several 100 nozzles. For this reason, it is difficult toproduce all the ink-jet recording heads such that they are completelyidentical.

Moreover, there is also the variation in the materials used. Forexample, in the case of the ink-jet printing device using the PZT, theamount of displacement varies according to the material and processtolerance of the PZT. As a result, it is unavoidable that the variationarises in the discharging characteristics of the individual recordingheads.

Conventionally, to obviate the above problem, the several methods havebeen proposed as disclosed in Japanese Laid-Open Patent Application Nos.2000-085158, 2000-263818, 07-089100, 07-323551, 08-118727, and11-020204.

The proposed methods of obviating the problem are mainly to change thevoltage, the drive time, etc. of the drive waveform and adjust the inkdrop speed and weight. However, if the drive waveform is changed, thereis the problem that the power consumption in the PZT or the heatingresistor may become large. Moreover, changing the drive waveform maymake the dot configuration itself change, may make the satellite dotoccur, or may make the dust occur, which will cause the image quality todeteriorate.

On the other hand, in the case of the thermal printing method, therecording head (the thermal recording head) in which the number ofheating elements are formed is used, and any of the heating elements ofthe recording head is selected based on the image data and driven togenerate heat, so that an image is formed on the thermal paper or theplain copy sheet.

The thermal printing device can record the image with the gradationlevels by driving the heating elements of the recording head based onthe multi-level image data and adjusting the heating energy, and doesnot need the post-processing, such as fixing, but has the features thatthe device size is small, the price is low, the noise at the time ofprinting is low, the operability is good, and the maintenance is easy toperform.

The recording head used for the thermal printing device may beclassified into the line printing type using the recording head in whicha large number of heating elements are arranged in a row according tothe width of the recording medium and the printing is performed thethermal paper which is conveyed perpendicularly to the heating elementrow, and the serial printing type using the recording head in which asmall number of heating elements are arranged in a row and the head isconveyed in the direction perpendicular to the moving direction of thethermal paper to perform the printing to the thermal paper.

Moreover, as for the thermal recording head, it is difficult to produceall the heating elements such that they are completely identical, andthere is also the variation in the heat generating characteristics ofthe individual recording heads.

DISCLOSURE OF THE INVENTION

A main object of the present invention is to provide an improvedprinting method and device in which the above-mentioned problems areeliminated.

Another object of the present invention is to provide a printing methodand device in which the variation in the recording heads is correctedwithout changing the driving conditions of the recording heads, such asthe ink-jet recording heads or the thermal recording heads.

Another object of the present invention is to provide a printing devicewhich does not have the difference in image quality between theindividual recording heads at the time of printing even if there is thedifference in the characteristics between the recording head, and whichcan obtain desirable image quality and does not create the satellitedot, the dust, etc., especially in the case of the ink-jet recordinghead.

Moreover, when the gamma correction parameter is chosen according to thelightness characteristics of the printed image to the difference in thecharacteristics of the individual recording heads, the yellow, forexample, has little change of lightness for the gradation levels of0-255, and the maximum change of the yellow is less than ten in thelightness. The variation in the recording heads cannot be detected withsufficient accuracy. Accordingly, another object of the presentinvention is to provide an image-processing method and a printing devicein which the gamma correction parameter is chosen with sufficientaccuracy in such a case and the same image quality is obtained for everyprinter.

In order to achieve the above-mentioned objects, the present inventionprovide an image-processing method for a printing device which has arecording head in which a plurality of printing elements are providedand drives the printing elements based on multi-level image data to forman image on an recording medium, the image-processing method comprisingthe steps of: selecting a gamma correction parameter according toprinting characteristics of the recording head; and forming an image onthe recording medium based on the selected gamma correction parameter.

In order to achieve the above-mentioned objects, the present inventionprovides a printing device which has a recording head in which aplurality of printing elements are provided and drives the printingelements based on multi-level image data to form an image on anrecording medium, the printing device comprising: a selection unitselecting a gamma correction parameter according to printingcharacteristics of the recording head; and an image forming unit formingan image on the recording medium based on the gamma correction parameterselected by the selection unit.

In order to achieve the above-mentioned objects, the present inventionprovides an image-processing method for a printing device which has arecording head in which a plurality of printing elements are providedand drives the printing elements based on multi-level image data to forman image on an recording medium, the image-processing method comprisingthe steps of: selecting a gamma correction parameter according tolightness characteristics of a printed image of the recording head; andforming an image on the recording medium based on the selected gammacorrection parameter.

In order to achieve the above-mentioned objects, the present inventionprovides a printing device which has a recording head in which aplurality of printing elements are provided and drives the printingelements based on multi-level image data to form an image on anrecording medium, the printing device comprising: a selection unitselecting a gamma correction parameter according to lightnesscharacteristics of a printed image of the recording head; and an imageforming unit forming an image on the recording medium based on the gammacorrection parameter selected by the selection unit.

In order to achieve the above-mentioned objects, the present inventionprovides an image-processing method for a printing device which has arecording head in which a plurality of printing elements are providedand drives the printing elements based on multi-level image data to forman image on an recording medium, the image-processing method comprisingthe steps of: selecting a gamma correction parameter according tooptical density characteristics of a printed image of the recordinghead; and forming an image on the recording medium based on the selectedgamma correction parameter.

In order to achieve the above-mentioned objects, the present inventionprovides a printing device which has a recording head in which aplurality of printing elements are provided and drives the printingelements based on multi-level image data to form an image on anrecording medium, the printing device comprising: a selection unitselecting a gamma correction parameter according to optical densitycharacteristics of a printed image of the recording head; and an imageforming unit forming an image on the recording medium based on the gammacorrection parameter selected by the selection unit.

In order to achieve the above-mentioned objects, the present inventionprovides an image-processing method for an ink-jet printing device whichhas an ink-jet recording head in which a plurality of nozzles areprovided and discharges ink drops from the plurality of nozzles based onmulti-level image data to form an image on an recording medium, theimage-processing method comprising the steps of: selecting a gammacorrection parameter according to discharging characteristics of theink-jet recording head; and forming an image on the recording mediumbased on the selected gamma correction parameter.

In order to achieve the above-mentioned objects, the present inventionprovides an ink-jet printing device which has an ink-jet recording headin which a plurality of nozzles are provided and discharges ink dropsfrom the plurality of nozzles based on multi-level image data to form animage on an recording medium, the ink-jet printing device comprising: aselection unit selecting a gamma correction parameter according todischarging characteristics of the ink-jet recording head; and an imageforming unit forming an image on the recording medium based on the gammacorrection parameter selected by the selection unit.

In order to achieve the above-mentioned objects, the present inventionprovides an image-processing method for an ink-jet printing device whichhas an ink-jet recording head in which a plurality of nozzles areprovided and discharges ink drops from the plurality of nozzles based onmulti-level image data to form an image on an recording medium,comprising the steps of: selecting a gamma correction parameteraccording to lightness of a printed image of the ink-jet recording head;and forming an image on the recording medium based on the selected gammacorrection parameter.

In order to achieve the above-mentioned objects, the present inventionprovides an ink-jet printing device which has an ink-jet recording headin which a plurality of nozzles are provided and discharges ink dropsfrom the plurality of nozzles based on multi-level image data to form animage on an recording medium, the ink-jet printing device comprising: aselection unit selecting a gamma correction parameter according tolightness of a printed image of the ink-jet recording head; and an imageforming unit forming an image on the recording medium based on the gammacorrection parameter selected by the selection unit.

In order to achieve the above-mentioned objects, the present inventionprovides an image-processing method for an ink-jet printing device whichhas an ink-jet recording head in which a plurality of nozzles areprovided and discharges ink drops from the plurality of nozzles based onmulti-level image data to form an image on an recording medium, themethod comprising the steps of: selecting a gamma correction parameteraccording to an optical density of a printed image of the ink-jetrecording head; and forming an image on the recording medium based onthe selected gamma correction parameter.

In order to achieve the above-mentioned objects, the present inventionprovides an ink-jet printing device which has an ink-jet recording headin which a plurality of nozzles are provided and discharges ink dropsfrom the plurality of nozzles based on multi-level image data to form animage on an recording medium, the ink-jet printing device comprising: aselection unit selecting a gamma correction parameter according to anoptical density of a printed image of the ink-jet recording head; and animage forming unit an image on the recording medium based on the gammacorrection parameter selected by the selection unit.

In order to achieve the above-mentioned objects, the present inventionprovides an ink-jet printing device which has a plurality of ink-jetrecording heads in which a plurality of nozzles are provided for eachink-jet recording head and discharges ink drops of a plurality of colorsfrom the plurality of nozzles of the plurality of ink-jet recordingheads respectively based on multi-level image data to form a color imageon an recording medium, each ink-jet recording head comprising: aselection unit selecting a gamma correction parameter of a correspondingcolor according to discharging characteristics of the ink-jet recordinghead.

In order to achieve the above-mentioned objects, the present inventionprovides an ink-jet printing device which has a plurality of ink-jetrecording heads in which a plurality of nozzles are provided for eachink-jet recording head and discharges ink drops of a plurality of colorsfrom the plurality of nozzles of the plurality of ink-jet recordingheads respectively based on multi-level image data to form a color imageon an recording medium, each ink-jet recording head comprising: aselection unit selecting a gamma correction parameter of a correspondingcolor according to lightness of the corresponding color of a printedimage of the ink-jet recording head.

In order to achieve the above-mentioned objects, the present inventionprovides an ink-jet printing device which has a plurality of ink-jetrecording heads in which a plurality of nozzles are provided for eachink-jet recording head and discharges ink drops of a plurality of colorsfrom the plurality of nozzles of the plurality of ink-jet recordingheads respectively based on multi-level image data to form a color imageon an recording medium, each ink-jet recording head comprising: aselection unit selecting a gamma correction parameter of a correspondingcolor according to an optical density of the corresponding color of aprinted image of the ink-jet recording head.

In order to achieve the above-mentioned objects, the present inventionprovides an image processing apparatus which communicates with anink-jet printing device, comprising: a requesting unit requesting agamma correction parameter or a kind thereof to the ink-jet printingdevice; a receiving unit receiving the gamma correction parameter or thekind thereof from the ink-jet printing device; and an image processingunit adjusting a gamma correction parameter based on the gammacorrection parameter or the kind thereof received by the receiving unit.

In order to achieve the above-mentioned objects, the present inventionprovides an image forming system including an image processing apparatusand an ink-jet printing device, the image processing apparatuscomprising: a requesting unit requesting a gamma correction parameterselection data to the ink-jet printing device; a receiving unitreceiving the gamma correction parameter selection data from the ink-jetprinting device; and an image processing unit selecting one of aplurality of gamma correction parameters based on the gamma correctionparameter selection data received by the receiving unit, and the ink-jetprinting device comprising: a storing unit storing the gamma correctionparameter selection data; and a transmitting unit transmitting the gammacorrection parameter selection data to the image processing apparatus.

In order to achieve the above-mentioned objects, the present inventionprovides an image forming method of an image forming system including animage processing apparatus and an ink-jet printing device, the imageforming method comprising the steps of: requesting a gamma correctionparameter selection data to the ink-jet printing device from the imageprocessing apparatus; creating the gamma correction parameter selectiondata by the ink-jet printing device; transmitting the created the gammacorrection parameter selection data to the image processing apparatus;receiving the gamma correction parameter selection data from the ink-jetprinting device by the image processing apparatus; and selecting a gammacorrection parameter based on the received gamma correction parameterselection data.

According to the present invention, as for the printing device which hasthe recording head in which the plurality of printing elements areformed, like an ink-jet recording head or a thermal recording head, anddrives the printing elements based on the multi-level image data to forman image on the recording medium, even if there is a variation in thecharacteristics of such recording heads, the variation can be correctedwithout changing the driving conditions of the recording head concernedsimply by selecting the gamma correction parameter according to thecharacteristics of the recording head concerned.

Moreover, even if there is a variation in the lightness characteristicsor the optical density of the printed image between such printingdevices, the variation can be corrected without changing the drivingconditions of the recording head concerned by selecting the gammacorrection parameter through the preparation of the color patch and thecolor measurement of the color patch, and thus the image formation isperformed and a constant image quality is obtained.

Moreover, even if there is a variation in the dischargingcharacteristics when the recording head is the ink-jet recording head,it is possible to correct the variation without changing the drivingconditions of the ink-jet recording head by measuring the dischargingcharacteristics of the recording head concerned and selecting the gammacorrection parameter. It is possible to obtain a desirable image qualitywithout generating the satellite dot, the dust, etc. in the formedimage, and no matter what ink-jet printing device performs the imageformation, the same image quality is obtained.

Furthermore, by carrying out the selection of the optimal gammacorrection parameter for each of the ink-jet recording heads of theplural colors and performing the image formation, the optical densityand the hue of the formed image remain unchanged no matter what ink-jetprinting device performs the image formation, and thus a high imagequality is obtained.

Other objects, features and advantages of the present invention will beapparent from the following detailed description when reading inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram showing the mechanical part of theink-jet printing device of the embodiment 1 in which the presentinvention is embodied.

FIG. 2A, FIG. 2B, and FIG. 2C are diagrams showing the recording headunit in the ink-jet printing device, wherein FIG. 2A is a perspectivediagram showing the whole recording head unit, FIG. 2B is an enlargedcross-sectional view of the nozzle part, and FIG. 2C is a diagramsshowing the arrangement of the plurality of nozzles on the nozzle plate.

FIG. 3 is a diagram for explaining the way the recording head unitdischarges the ink drops to the paper.

FIG. 4 is a block diagram showing the functional composition of the hostcomputer and the ink-jet printing device.

FIG. 5 is a block diagram showing the control unit of the ink-jetprinting device of the embodiment 1.

FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6D are diagrams showing the drivewaveform of the recording head.

FIG. 7 is a diagram showing the composition of the drive circuit of therecording head.

FIG. 8 is a diagram showing the example of the driver IC.

FIG. 9 is a diagram for explaining the relation between the gradationlevel and the lightness in the recording head.

FIG. 10A and FIG. 10B are diagrams for explaining the examples of thegamma correction table.

FIG. 11 is a diagram showing the results of measurement of the relationbetween the gradation level and the lightness when the optimal gammacorrection parameter is selected and the different recording heads areused.

FIG. 12 is a diagram showing the relation between the gradation leveland the lightness for every color, and the variation thereof.

FIG. 13 is a diagram showing the relation between the gradation leveland the optical density of the yellow Y, and the variation.

FIG. 14 is a diagram showing the relation between the gradation leveland the optical density in the recording head.

FIG. 15 is a diagram showing the results of measurement of the relationbetween the gradation level and the lightness when the optimal gammacorrection parameter is selected and the different recording heads areused.

FIG. 16 is a diagram showing the relation between the gradation leveland the optical density in the different head.

FIG. 17 is a diagram showing the relation between the gradation leveland the optical density for every color, and the variation thereof.

FIG. 18 is a block diagram showing the composition of the image formingsystem of the embodiment 11.

FIG. 19 is a perspective view of the principal part of the thermalprinting device of the embodiment 13.

BEST MODE FOR CARRYING OUT THE INVENTION

A description will now be given of the preferred embodiments of theinvention with reference to the accompanying drawings.

With reference to FIG. 1 through FIG. 5, the ink-jet printing device inthe first preferred embodiment of the present invention will beexplained.

FIG. 1 shows the composition of the mechanical part of the ink-jetprinting device as the serial printer in which the present invention isembodied. FIG. 2A, FIG. 2B, and FIG. 2C are diagrams showing therecording head unit in the ink-jet printing device, wherein FIG. 2A is aperspective diagram showing the whole recording head unit, FIG. 2B is anenlarged cross-sectional view of the nozzle part, and FIG. 2C is adiagram showing the arrangement of the plurality of nozzles on thenozzle plate. FIG. 3 is a diagram for explaining the way the recordinghead unit discharges the ink drops to the paper.

The ink-jet printing device of this embodiment comprises the frame 1,the guide rails 2 and 3, the carriage 4, and the printing head 5. Theguide rails 2 and 3 are constructed horizontally across the frame 1. Thecarriage 4 is movably connected to the guide rails 2 and 3 so that themovement of the carriage 4 in the direction indicated by the arrow A inFIG. 1 is possible. The printing head 5 is carried on the carriage 4.The movement of the carriage 4 in the direction of the arrow A is drivenby the power source (which is not shown), such as the motor.

The paper (recording paper) 7 which is the printing medium is placedonto the guide board 6, and the paper 7 is received by the platen 10.The platen 10 is equipped with the feeding knob 10 a which is rotatedthrough the drive gear 8 and the sprocket gear 9 by the power sourcewhich is not illustrated. Conveyance of the paper 7 in the directionindicated by the arrow B in FIG. 1 is allowed by the pressure roller 11while the paper 7 is compressed between the pressure roller 11 and theperipheral surface of the platen 10 under pressure.

In the ink-jet printing device of this embodiment, the movement orscanning of the printing head 5 (carriage 4) is carried out in the mainscanning direction (the direction of the arrow A) while the conveyanceof the paper 7 is carried out in the sub-scanning direction (thedirection of the arrow B) so that the ink drop is discharged from theprinting head 5 and an image is printed on the paper 7.

A description will be given of the carriage 4, the printing head 5, theink supply system, etc. in the following.

The carriage 4 is equipped with the printing head 5. The printing head 5comprises the ink-jet heads which carry out the discharging of the inkdrop of each of the colors of yellow (Y), cyan (C), magenta (M) andblack (Bk) respectively, and the plurality of ink discharge outputs arearranged in the ink-jet heads in the direction which is perpendicular tothe main scanning direction, and the head 5 is mounted with thedirection of the discharge of the ink drop being the downward direction.In addition, the respective ink cartridges for supplying the ink of eachcolor to the printing head 5 are mounted on the carriage 4 in such amanner that they are exchangeable.

The ink cartridge is provided at the top with the air outlet open to theatmosphere, and provided at the bottom with the ink supply outlet forsupplying the ink to the ink-jet head inside. The ink cartridge containsthe porosity object inside, and this porosity object being filled withthe ink. The ink of the ink cartridge being supplied to the ink-jet headis maintained at a slightly negative pressure by the capillary tubepower of the porosity object.

Moreover, the printing head in the present embodiment is constructedusing the separate ink-jet heads of the individual color component inks.Alternatively, the printing head may be constructed as one headcomposition which has the nozzle sequence which carries out thedischarge of the ink drop of each color.

Furthermore, in the printing head (ink-jet head) 5, the ink ispressurized and the ink drop is made to form. Although the electrostatictype which is made to carry out displacement of the diaphragm andcarries out ink pressurization by the static electricity power betweenthe diaphragm which forms the liquid-chamber surface of a wall byelectromechanical transducers, such as the piezoelectric element, andforms the piezoelectricity type or the ink passage surface of a wallwhich carries out ink pressurization through the diaphragm, and theelectrode which counters this can be used.

In the present embodiment, a description will be given the case in whichthe piezoelectric type ink-jet head is used.

As shown in FIG. 2B, the printing head 5 is provided so that the nozzleplate 14 in which the plurality of nozzles 15 are formed is attached tothe front surface of the liquid-chamber forming member 13 which formsthe liquid chamber 12.

By giving the pressure to the ink in the liquid chamber 12 by theactuator which is the energy occurrence unit by the piezoelectric devicewhich is not illustrated, the ink in the liquid chamber 12 serves as theink drop 16 from the nozzle 15 of the nozzle plate 14, flies, andadheres to the paper 7 as a dot.

At this time, the desired image is printable by driving selectively theactuator which gives the pressure to each liquid chamber 12.

In this printing head 5, the plurality of nozzles 15 constitute theplurality of dot formation units, and the sequence (nozzle sequence) ofthe nozzle 15 is made to intersect perpendicularly to the main scanningdirection, and the pitch between the nozzles 15-15 is represented by2×Pn.

Moreover, the nozzles on one recording head are arranged in twosequences with the nozzle sequence distance L. It is shifting, beingconfigured alternately and using the nozzle sequence of the twosequences Pn, and the nozzle sequence of the two sequences can form theimage of the pitch Pn in the sub-scanning direction by one scanning andthe feed.

Moreover, in order to carry out the movement or scanning of the carriage4 in the main scanning direction, the drive pulley driven and rotated bythe scanning motor and the follower pulley are connected together by thetiming belt, and by fixing this timing belt to the carriage, the two-waymovement of the carriage is carried out according to the forward orreverse rotation of the scanning motor.

On the other hand, in order to convey the paper set on the guide boardto the printing part of the printing head, there are provided the feedroller and friction pad which delivers the paper from the guide board,the guide member which guides the conveyance of the paper, theconveyance roller which conveys the paper from the feed roller, and thetip roller which specifies the delivery angle of the paper from theconveyance roller forced on the peripheral surface of this conveyanceroller and the conveyance roller.

The conveyance roller is driven and rotated by the feed roller throughthe gear train. And the platen roller is configured in order to guidethe paper sent out from the conveyance roller corresponding to thesuccessive range of the main scanning direction of the carriage to theprinting part of the printing head (guide).

Furthermore, at the downstream part of the printing receptacle in thepaper conveyance direction, the conveyance roller which is rotated anddriven in order to send out the paper in the ejection direction, and thespur are arranged. Further arranged are the ejection roller for sendingout the paper to the ejection tray, the spur, the guide member forsecuring the ejection course of the paper, etc.

The printing head is made to drive according to the image signal at thetime of printing, moving the carriage 4. The ink is breathed out in thestopped paper, the one line is printed, and the following line isprinted for the paper after predetermined quantity conveyance.

At the time of the printing end, by receiving the printing end signal orthe signal with which the back end of the paper arrived at the printingregion, printing operation is terminated and the paper is delivered tothe paper.

Moreover, in the position which separated from the printing region bythe side of the transfer direction right end of the carriage, therecovery processing device which is not illustrated for recovering thepoor discharge of the printing head is configured.

To the recovery processing device, it has the cap unit, the suctionunit, and the cleaning unit. During printing standby, it transfers atthis recovery processing device side, and capping of the head is carriedout with the capping unit, and the carriage can prevent the poor inkdischarge by ink dryness by maintaining discharge outlet at the humidstate.

Moreover, by carrying out the discharge of the ink which is not relatedto printing in the middle of printing etc., the ink viscosity in alldischarge outputs becomes fixed, and the stable discharge performance ismaintained.

When the poor discharge occurs, the discharge outlet of the head issealed with the capping unit, air bubbles etc. are sucked out of thedischarge outlet with the ink with the suction unit through the innertube, the ink, garbage, etc. adhering to the discharge outlet face areremoved by the cleaning unit, and the poor discharge is recovered.

Moreover, the attracted ink is sent to the consumed ink tank (not shown)installed on the main part bottom, and absorbed and retained by the inkabsorber inside the consumed ink tank.

FIG. 4 shows the functional composition of the host computer and theink-jet printing device. As shown in FIG. 4, the printing device of thepresent embodiment is not provided with the function of generating thedot pattern actually printed in response to the print command of thecharacter or image drawing. That is, the print command from theapplication software executed on the host computer is processed by theprint driver incorporated as the software in the host computer, andrasterized to the data of the printing dot pattern, and such data istransmitted to the printing device so that the printing is performed.

Specifically, the print command of the character or image drawing fromthe application or the operating system in the host computer (forexample, the command in which the position, the thickness, the form,etc. of the line to be recorded are described, or the command in whichthe font, the size, the position of the character to be recorded, etc.)of the character is stored temporarily in the drawing data memory. Inaddition, these commands are described in the specific print language.

The command stored in the drawing data memory is interpreted by therasterizer. If it is the command to print a line, it is transformed intothe printing dot pattern according to the position, the thickness, etc.of the line which are specified by the command. If it is the command toprint a character, the outline information of the correspondingcharacter is called from the font outline data stored in the hostcomputer, and the outline information is transformed into the printingdot pattern according to the size and the position of the characterwhich are specified by the command. Such rasterized dot patterns arestored in the raster data memory.

At this time, the host computer functions to rasterize the command orthe outline information into the data of the printing dot pattern byusing the known rectangular lattice as the basic printing position. Theprinting dot pattern stored in the raster data memory is transmitted tothe ink-jet printing device via the interface.

FIG. 5 shows the composition of the control unit of the ink-jet printingdevice of the embodiment 1.

As shown in FIG. 5, the control unit of the ink-jet printing devicecomprises the printing control unit 18, the head driving unit 19 whichdrives each actuator of the printing head 5, the carriage drive controlunit 20 which carries out driving control of the carriage 4, the linefeed drive control unit 21 which carries out the rotation driving of theplaten 10, and the data-processing unit 17.

The printing data sent from the host computer is stored in the rasterdata memory (which is not illustrated). After the predetermined data isreceived, the stored printing data is supplied via the data-processingunit 17 to the head driving unit 19 so that the ink drop is dischargedfrom the predetermined nozzle outlet 15 of the printing head 5 based onthe printing dot data, the image according to the printing data isprinted on the paper 7. At the same time, the rotation of the platen 10or the conveyance of the paper 7 (the sub-scanning) is controlledthrough the line feed drive control unit 21 and the movement of thecarriage 4 (the main scanning) is controlled through the carriage drivecontrol unit 20.

When the printing on the plain paper is performed by the conventionalink-jet printing device, several image quality problems peculiar to theink-jet printing arise, such as the color-reproduction characteristic,the durability, the light resistance, the ink dryness characteristic,the character blot (feathering), the color boundary blot (colorbleeding), the double-sided printing characteristic, etc. of the image.Furthermore, when the high-speed printing on the plain paper is carriedout, it is very difficult to satisfy all these characteristics.

Moreover, the ink commonly used for the ink-jet printing contains thewater as the major component, the colorant, and the wetting agents, suchas glycerol, for the purpose of prevention of clogging.

As the colorant, there are the dye and the pigment. And the dye basedink is conventionally used in many cases for the color part from thereason that the outstanding coloring characteristic and stability areacquired.

However, if the recording paper only for the ink jet printing in whichsolidity, such as the light resistance of the image obtained using colorsystem ink and durability, is inferior to the colorant to the thingusing the pigment and which has the ink absorption layer especiallyabout durability is used, although it will become possible to aim at acertain amount of improvement, when the plain paper is used, it iscommon that it is not that which may be satisfactory.

Then, in order to improve the problem over the color system ink in thecase where the plain paper is used in recent years, examination orutilization is carried out for use of the pigment system ink which usesthe organic pigment, the carbon black, etc. as the colorant to the plainpaper printing.

Since the pigment does not have the solubility to the water unlike thecolor, usually, it mixes and carries out the distributed processing ofthe pigment with the dispersant, and is used for the water as water inkin the state where stable dispersion is carried out.

Generally, using the pigment allows the light resistance and waterproofimprovement to be obtained. However, it is difficult to satisfy theother image quality characteristics simultaneously. Especially, it isdifficult to obtain high quality image concentration, sufficientcoloring characteristic, color-reproduction characteristic, etc. whencarrying out the high-speed printing on the plain paper. There have beenstill the image quality problems that are not fully satisfactory, suchas the character blot, the color boundary blot, the double-sidedprinting characteristic, the ink dryness characteristic (fixingcharacteristic), etc.

A description will be given of the composition of the ink according tothe present invention. The ink drop according to the present inventionemploys the printing ink which has the following composition.

That is, the pigment is used as the colorant for printing, and thesolvent for decomposing and distributing the pigment is used as theindispensable ingredient. And the wetting agents, the surface activeagent, the emulsion, the antiseptics, and the pH adjustment agent arefurther used as the additives. The wetting agent 1 and the wetting agent2 are mixed because viscosity adjustment can be performed easily and therespective features of the wetting agents can be harnessed. Namely, theink according to the present invention is essentially composed of thefollowing elements (1) to (10):

(1) Pigment (self-dispersibility pigment) 6 wt % or more;

(2) Wetting agent 1;

(3) Wetting agent 2;

(4) Water-soluble organic solvent;

(5) Surface active agent of anionic or nonionic type;

(6) Polyol or glycol ether with the carbon number of eight or more;

(7) Emulsion;

(8) Antiseptics;

(9) pH adjustment agent;

(10) Pure water.

Hereafter, each of the elements of the ink according to the presentinvention will be explained.

(1) Concerning the pigment, the inorganic pigment and the organicpigment may be used without limiting the kind of the pigment. Theexamples of the inorganic pigment used may include titanium oxide, ironoxide, and further include the carbon black which is manufactured byusing the well-known methods, such as the contacting method, the furnacemethod, and the thermal method.

Moreover, the examples of the organic pigment used may include the azopigments (for example, azo lake, insoluble azo pigment, condensation azopigment, chelate azo pigment, etc.), the multi-ring type pigments (forexample, phthalocyanine pigment, perylene pigment, perynone pigment,anthraquinone pigment, quinacridone pigment, dioxazine pigment,thioindigo pigment, iso-indolinone pigment, quinophtharone pigment,etc.), the dye chelates (for example, the basic dye type chelate, theacid dye type chelate, etc.), the nitro pigments, the nitroso pigments,the aniline black, etc.

According to the preferred embodiment of the invention, any of thesepigments which have a desirable affinity with the water is preferablyused. The grain size of the pigment used is desirably in the range of0.05 to 10 micrometers, and more preferably, 1 micrometer or less, andmost preferably, 0.16 micrometers or less.

The amount of addition of the pigment as the colorant in the ink isdesirably in the range of about 6 to 20% by weight, and more preferablyin the range of about 8 to 12% by weight.

The following are mentioned as the examples of the pigment preferablyused according to the present invention.

The examples of the black pigment used may include the carbon black (C.I. pigment black 7), such as the furnace black, the lamp black, theacetylene black, and the channel black, the metals, such as copper, iron(C. I. pigment black 11), and titanium oxide, and the organic pigments,such as the aniline black (C. I. pigment black 1).

Moreover, the examples of the color pigments may include the C.I.pigment yellow 1 (First yellow G), 3, 12 (Diarylide yellow YT 553D), 13,14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 81, 83(Permanent yellow HR), 95, 97, 98, 100, 101, 104, 408, 109, 110, 117,120, 138, 153, the C.I. pigment oranges 5, 13, 16, 17, 36, 43, 51, theC.I. pigment red 1, 2, 3, 5, 17, 22 (Brilliant first Scarlett), 23, 31,38, 48:2 (Permanent red 2B (Ba)), 48:2 (Permanent red 2B (calcium)) 48:3(Permanent red 2B (Sr)), 48:4 (permanent red 2B (Mn)), 49:1, 52:2, 53:1,57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81 (Rhodamine 6Glake), 83, 88,101 (Iron oxide red), 104, 105, 106, 108 (Cadmium red),112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172,177, 178, 179, 185, 190, 193, 209, 219, the C.I. pigment violet 1(Rhodamine lake), 3, 5:1, 16, 19, 23, 38, the C.I. pigment blue 1, 2, 15(Phthalocyanine blue R), 15:1, 15:2, 15:3 (Phthalocyanine blue E), 16,17:1, 56, 60, 63, the C.I. pigment greens 1, 4, 7, 8, 10, 17, 18, 36,etc.

In addition, the surface of the pigment (for example, carbon) isprocessed by the resin etc., and the graft pigment which is dispersiblein water, the processed pigment which is dispersible in water with thefunctional groups, such as sulfone group or carboxyl group, which areadded to the surface of the pigment (for example, carbon) may be used.

Moreover, the microcapsule which is made to contain the pigment suchthat the pigment can be dispersed in water may be used.

According to the preferred embodiment of the invention, it is desirablethat the pigment for black ink and the dispersant are added to the inkas the pigment dispersion liquid which is made to disperse the pigmentin the water medium. The desirable example of the dispersant used may bethe known dispersion liquid used for adjusting the known pigmentdispersion liquid.

The examples of the dispersion liquid used may include the following:poly-acrylic acid, poly-methacrylic acid, acrylic acid-acrylonitrilecopolymer, vinyl acetate acrylic acid ester copolymer, acrylicacid-acrylic acid alkyl ester copolymer, styrene acrylic acid copolymer,styrene methacrylic acid copolymer, styrene acrylic acid-acrylic acidalkyl ester copolymer, styrene methacrylic acid-acrylic acid alkyl estercopolymer, styrene-alpha-methyl styrene acrylic acid copolymer, styrenealpha-methyl styrene acrylic acid copolymer-acrylic acid alkyl estercopolymer, styrene maleic acid copolymer, the vinyl-polymers naphthalenemaleic acid copolymer, vinyl acetate ethylene copolymer, vinyl acetatefatty acid vinyl-polymers ethylene copolymer, vinyl acetate maleatecopolymer, vinyl acetate crotonic acid copolymer, vinyl acetate acrylicacid copolymer, etc.

According to the preferred embodiment of the invention, the averagemolecular weight of any of these copolymers used is desirably in therange of 3,000 to 50,000, more preferably, in the range of 5,000 to30,000, and most preferably in the range of 7,000 to 15,000. The amountof addition of the dispersant used may be in such a range that thepigment is dispersed stably without affecting the effects of theinvention. The ratio of the pigment to the dispersant is desirably inthe range of 1:0.06 to 1:3 is desirable, and more preferably in therange of 1:0.125 to 1:3.

The ratio of the pigment used for the colorant to the total weight ofthe printing ink is in the range of 6% to 20% by weight, and the grainsize of the colorant pigment is in the range of 0.05 micrometers to 0.16micrometers. The pigment is dispersed in water, and the dispersant isthe macromolecule dispersant the molecular weight of which is in therange of 5,000 to 100,000. If the water-soluble organic solventcontaining the pyrolidone derivative, especially 2-pyrolidone is usedfor at least one of the color inks, the image quality will improve.

(2) to (4) Concerning the wetting agent 1, the wetting agent 2 and thewater-soluble organic solvent, the water is used as a liquid medium inthe ink. In order to obtain the desired physical properties of the inkand to prevent dryness of the ink, and in order to improve thedissolution stability etc., the examples of the water-soluble organicsolvent used may include the following. It is possible to use thesewater-soluble organic solvents by mixing the plurality of solvents.

The examples of the wetting agents 1 and 2 and the water-soluble organicsolvent used may include the following: the polyhydric alcohols, such asethylene glycol, di-ethylene glycol, tri-ethylene glycol, propyleneglycol, di-propyrene glycol, tri-propyrene glycol, tetra-ethyleneglycol, hexylene glycol, polyethylene glycol, polypropylene glycol,1,5-pentanediol, 1,6-hexanediol, glycerol, 1,2,6-hexanetriol,1,2,4-butanetriol, 1,2,3-butanetriol, petriol; the polyhydric alcoholalkyl esters, such as ethylene glycol mono-ethyl ether, ethylene glycolmono-butyl ether, di-ethylene glycol mono-methyl ether, di-ethyleneglycol mono-ethyl ether, di-ethylene glycol mono-butyl ether,tetra-ethylene glycol mono-methyl ether, propylene glycol mono-ethylether; the polyhydric alcohol allyl ethers, such as ethylene glycolmono-phenyl ether, ethylene glycol mono-benzyl ether; thenitrogen-including multi-ring compounds, such as 2-pyrolidone,N-methyl-2-pyrolidone, N-hydroxyethyl-2-pyrolidone,1,3-dimethylimidazolidinone, epsilon-caprolactam, gamma-butyrolactone;the amide compounds, such as formamide, N-methyl formamide, N,N-dimethylformamide; the amine compounds, such as mono-ethanol amine, di-ethanolamine, tri-ethanol amine, mono-ethyl amine, di-methyl amine, tri-ethylamine; the sulfur-including compounds, such as di-methyl sulfoxide,sulfolane, thiodiethanol; propylene carbonate, carbonic acid ethylene,etc.

The desirable examples of these organic solvents may include diethyleneglycol, thiodiethanol, polyethylene glycol 200-600, triethylene glycol,glycerol, 1,2,6-hexanetriol, 1,2,4-buthanetriol, petriol,1,5-penthanediol, 2-pyrolidone, and N-methyl-2-pyrolidone. These areeffective in solubility and prevention of the poor dischargingcharacteristic due to the moisture evaporation.

The other wetting agents suitably used may contain the saccharide. Theexamples of the saccharide used may include the monosaccharides, thedisaccharide, the oligosaccharides (the trisaccharide andquatrosaccharide are included), and the polysaccharides. The desirableexamples of the polysaccharides may include the glucose, the mannose,the fructose, the ribose, the xylose, the arabinose, the galactose, themaltose, the cellobiose, the lactose, the sucrose, the trehalose, themaltotriose, etc. Here, the polysaccharide means the sugar in the widesense and suppose that it includes the substances which widely exist inthe nature, such as alpha-cyclodextrin, cellulose, etc.

Moreover, the examples of the derivatives of these saccharides mayinclude the reducing sugar (for example, the sugar alcohol (generalformula: HOCH2(CHOH)nCH2OH where n is the integer of 2 to 5), theoxidation sugar (for example, the aldon acid, the uron acid, etc.), theamino acid, the thio acid, etc. Especially the sugar alcohol isdesirable and the desirable examples of the sugar alcohol may includethe Maltitol, the Sorbit, etc.

The content of the saccharides in the ink is desirably in the range of0.1 to 40% by weight, and more preferably in the range of 0.5-30% byweight.

(5) Concerning the anionic or nonionic surface active agent, any agentmay be used without limiting the kind of the surface active agent. Theexamples of the anionic surface active agent used may includepolyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauricacid salt, polyoxyethylene alkyl ether sulfate, etc.

The examples of the nonionic surface active agent may includepolyoxyethylene alkyl ether, polyoxyethylene alkyl ester,polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenylether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, etc.One of the above examples of the surface active agents may be usedsolely or the plurality of among them may be mixed in combination.

The surface tension according to the present invention is an index whichdenotes the permeability to paper. Specifically, it means the dynamicsurface tension for the short time within one second after the surfaceis formed, and it differs from the static surface tension measured bythe saturation time.

Although any method of measuring the dynamic surface tension, such asthe conventional measuring method which is known from Japanese Laid-Openpatent Application No. 63-31237, can be used, the surface tensionmeasuring instrument of Wilhelmy hung-board type is used to measure thedynamic surface tension according to the present invention.

The desirable value of the surface tension which allows excellent fixingcharacteristic and dryness characteristic is smaller than 40 mJ/m², andmore preferably it is smaller than 35 mJ/m².

(6) Concerning the polyol or glycol ether with the carbon number ofeight or more, the polyol and/or glycol ether which is partiallywater-soluble and has the solubility in a range of 0.1 to 4.5% by weightin water at 25-degree C. is added so that the ratio of the content ofthe polyol and/or glycol ether to the total weight of the printing inkis in the range of 0.1 to 10.0% by weight. It is turned out that if theabove conditions are met, the wettability to the heat element of the inkis improved and the discharge stability and frequency stability areacquired with a small amount of addition.

(6-1) 2-ethyl-1,3-hexanediol; solubility:4.2% (20 degrees C.)

(6-2) 2,2,4-trimethyl-1,3-pentanediol; solubility: 2.0% (25 degrees C.)

The penetrant which has the solubility in the range of 0.1 to 4.5% byweight in water at 25-degree C. is advantageous in that the permeabilityis high in spite of low solubility. Therefore, it is possible to producethe ink which has high permeability, with the other solvent incombination with the penetrant having the solubility in the range of0.1-4.5% by weight in water at 25-degree C., or in combination with theother surface active agent.

(7) Concerning the emulsion, it is desirable that the resin emulsion beadded to the ink according to the present invention. The resin emulsionmeans the emulsion whose continuation phase is the water and whosedispersion phase is one of the following resin ingredients. The examplesof the resin ingredients of the dispersion phase of the resin emulsionused may include the acrylic resin, the vinyl acetate resin, thestyrene-butadiene resin, the vinyl chloride resin, the acrylic styreneresin, the butadiene resin, the styrene resin, etc.

According to the preferred embodiment of the invention, it is desirablethat the resin is the polymer having both the hydrophilic portion andthe hydrophobic portion.

Moreover, although the grain size of the resin is not limited as long asthe emulsion is formed, the desirable diameter of the grain of the resinis about 150 nm or less, and more preferably is in the range of 5 to 100nm. In these resin emulsions, the resin particles can be obtained bymixing in the water with the surface active agent in some case.

For example, the emulsion of the acrylic resin or the styrene-acrylicresin can be obtained by mixing (meta) acrylic acid ester and thesurface active agent with (meta) acrylic acid ester or styrene, and insome case (meta) acrylic acid (meta) ester in the water.

The rate of mixture with the resin ingredients and the surface activeagent is desirably in the range of 10:1 to 5:1. The formation of theemulsion becomes difficult when the amount of the surface active agentused does not reach the range. On the other hand, when the amount of thesurface active agent used exceeds the range, the durability of the inkfalls or there is the tendency for permeability to get worse.

The rate of the weight parts of the water to 100 weight parts of theresin in the dispersion phase of the resin emulsion is desirably in therange of 60 to 400, and more preferably in the range of 100 to 200. Theexamples of the commercially available resin emulsions may include“maikuro-jeru” E-1002 and E-5002 (styrene acrylic resin emulsion, NipponPaint Co., Ltd.), “bonkohto” 4001 (acrylic resin emulsion, Dainippon Ink& Chemicals Inc.), “bonkohto” 5454 (styrene acrylic resin emulsion,Dainippon Ink & Chemicals Inc.), SAE-1014 (styrene acrylic resinemulsion, Nippon Zeon Co., Ltd.), “saibinohru” SK-200 (acrylic resinemulsion, Saiden Chemistry Co., Ltd.), etc.

In the ink used according to the present invention, the ratio of thecontent of the resin ingredients of the resin emulsion to the ink isdesirably in the range of 0.1-40% by weight, and more preferably in therange of 1-25% by weight.

The resin emulsion has the character thickened and condensed, inhibitsthe osmosis of the coloring ingredients, and further has the effectwhich promotes fixing to the printing medium.

Moreover, depending on the kind of resin emulsion, the coat is formed onrecord material, and it has the effect which also raises the frictionresistance of the printed matter.

(8) to (10) The known additives in the art, other than the colorant, thesolvent, and the surface active agent, can be added to the ink accordingto the present invention.

The examples of the antiseptics or antimold used may includedehydroacetic acid sodium, sorbic acid sodium, 2-pyridinethiol-1-oxidesodium, benzoic acid sodium, pentachlorophenol sodium, etc.

Concerning the pH adjustment agent, any arbitrary substances can be usedif the pH value of the ink can be adjusted to be seven or more withoutaffecting the ink prepared. The examples of the pH adjustment agent usedmay include the amines, such as diethanol amine and triethanol amine,the carbonates of alkali metals, such as lithium carbonate, sodiumcarbonate and potassium carbonate, the hydroxides of alkali metals,lithium hydroxide, sodium hydroxide, potassium hydroxide, ammoniumhydroxide, the 4th class ammonium hydroxide, the 4th class phosphoniumhydroxide, etc.

The examples of the chelating reagent used may includesethylene-diamine-tetraacetic acid sodium, nitrilo-triacetic acid sodium,hydroxyethyl ethylenediamine-triacetic acid sodium,diethylene-triamine-pentaacetic acid sodium, uramildiacetic acid sodium,etc.

The examples of the anticorrosive used may include acid sulfite, sodiumthiosulfate, ammonium thiodiglycolate, diisopropylamine nitrite,pentaerythritol tetranitrate, dicyclohexylamine nitrite, etc.

Next, the method of correcting the variation between the recording headsof the discharging characteristics of the present invention will beexplained.

FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6D show the drive waveform of therecording head, FIG. 7 shows the drive circuit (which corresponds to thehead drive unit shown in FIG. 5) of the recording head, and FIG. 8 showsthe example of the driver IC.

In the data-processing unit 17 of FIG. 5, and the printing control unit18, the each-direction transformation corresponding to the row of theprinting head and the creation of the 2-bit drive data signal requiredin order to have desirable control of striking the printing head in anydirection to the large drop, the small drop, and the three non-printingvalues are performed, and printing data is sent to the head drivecircuit according to the drive periodicity of the recording head as adrive data signal S2.

Therefore, as a drive data signal S2, it becomes the number twice thenumber of the bits of the channels. As the signal sent to the head drivecircuit is the drive data.

The latch signal S1 for retaining in the latch circuit 30, when theclock signal S3 for making it shift by the shift register 29 in thedriver IC 27 and the drive data in the shift register are assembled thenumber of the channels, the dot of the size which forms the image dotfor the drive waveform.

The drive waveform pulsing signal (M1-M3) for choosing the drivewaveform (FIG. 6D) corresponding to the (large drop) and the drivewaveform (FIG. 6B) corresponding to the small drop is sent.

On the other hand, as the drive waveform creation unit 23 which createsthe drive waveform shown in FIG. 6A, transform the drive waveform data(digital signal) from CPU22 into the analog signal by D/A converter 24,and pass the amplifier 25 which amplifies this to actual drive voltage,and the current amplifier 26 for supplying the drive electric current ofthe recording head enough further—the drive waveform as shown in FIG. 6Ais inputted into pinch off voltage of the driver IC 27.

In the driver IC 27, according to the drive data S2, one of the drivewaveform pulsing signals (M1-M3, logic signal) is chosen by the dataselector 31, and it is inputted into the gate of the transmission gate33 which is the switching unit through the level shifter 32 whichtransforms the logic signal into the drive voltage level.

Therefore, the transmission gate 33 will be switched according to thelength of the selected drive waveform pulsing signal, and the waveformof FIG. 6B for small drops and the waveform of FIG. 6D for large dropswill be outputted to the output terminal (at the driver IC shown in FIG.8, it is 34-1 to 34-192).

Moreover, in this embodiment, the drive waveform of FIG. 6C for mediumdrops can also be chosen.

According to these waveforms, PZT28 drives and can have desirablecontrol of striking the small drop and the large drop in any direction.

In this embodiment—one drive waveform:FIG. 6—since the object for smalldrops, the object for inside drops, wave:FIG. 6B for large drops, FIG.6C, and FIG. 6D are created from (A), the circuit and signal line whichsupply the drive waveform are desirable at one, and the miniaturizationof the cost reduction, the circuit board, and the transmission line canbe attained.

Although this drive waveform is optimized and the variation between therecording heads is corrected conventionally, in the present invention,change is not added to the drive waveform but the variation between theheads is corrected by the image-processing method.

Next, the image processing method will be explained in more detail.

FIG. 9 shows the result which changed the recording head, printed thecolor patch of middle the optical density (gradation levels 0-255) byimage processing of gamma through and the dithering matrix, and measuredthe lightness.

Change considered only as the recording head, and the driving conditions(drive waveform, drive frequency), kind of recording paper, etc. are thesame, and are printed.

The measurement of lightness—the gradation levels 0, 2, and 4 and . . .0-254 measured every gradation level 2 in the condition of 250, 252,254, and 255, and, finally measured the gradation level 255 in it.

X-Rite938 of X-Rite is used for measurement of the lightness shown inFIG. 9.

Since it is the variation in each printing head when the printing headchanges so that I may be understood from FIG. 9, it is understood thatthe difference is in the lightness acquired also on the same drivingconditions.

On the other hand, in the present invention, the gamma correction tableis changed and the optimal gamma parameter for each recording head ischosen.

FIG. 10A and FIG. 10B show the example of the gamma correction table.

Although the gamma curve has width within the recess, FIG. 10A is notwhat is restricted to this, and may be able to be chosen from the recessto the projection like FIG. 10B.

These are decided by the characteristics of the ink-jet recording head.The plurality of gamma correction parameters are beforehand stored bythe ink jet printer of the present invention, or the printer driver.

The gamma correction parameter is the table in which the output value isset up to the gradation levels 0-255. When performing image processingby the ink jet printer side, it is necessary to also memorize theplurality of gamma correction parameters in the ink jet printer, andthey are usually stored by the memories, such as ROM.

Moreover, as shown in FIG. 4, when the gamma correction is performed bythe printer driver of PC, the storage apparatus, such as the hard diskin PC, memorize.

According to the gamma correction parameter chosen from the plurality ofgamma correction parameters which preserved the case where the latterprinter driver performed image processing when the concrete embodimentis described further at the example for being the best for the ink-jetrecording head, the printer driver performs image processing to theimage data of the color patch, and outputs the image data to the ink jetprinter.

In the ink jet printer side, according to the image data which received,the recording head is driven and the color patch is outputted to therecording paper.

FIG. 11 shows the results of measurement of the relation between thegradation level and the lightness to the plurality of recording headsusing the recording head which chose the respectively optimal gammacorrection parameter.

Even if it changed the recording head as shown in FIG. 11 when thelightness is measured, the profile of the almost same lightness is ableto be obtained.

Consequently, by performing image processing in the printer or printerdriver using the selected gamma correction parameter, when the ink jetprinter is created by these recording heads, even if which ink jetprinter performed image creation, the almost same image quality isobtained.

Moreover, in this embodiment, the gamma correction parameter can bechosen very easily only by creating and carrying out the colormeasurement of the image of the color patch, without disassemblingespecially the device, since the variation between the recording headsis detected by measuring lightness and the optimal gamma correctiontable is chosen.

Moreover, not in the recording head simple substance but in the statewhere it had been constructed as a printer, since the gamma correctionparameter can be chosen, for example, it can carry out easily even inthe assembly line of the factory, assembles, and becomes shortening ofinspection time.

Moreover, it becomes possible not only the process of the factory butfor the user to carry out.

Next, the example which measures lightness on one gradation level willbe explained as the ink-jet printing device of the embodiment 2.

When there is the relation that the different profiles of the gradationlevels of the recording head and lightness do not cross so that I may beunderstood from the relation of the gradation level and lightness asshown in FIG. 9 (this relation is generally realized), it is measuringthe lightness of the gradation level of one somewhere, and it ispossible for it to be decided uniquely of which profile it will be therelation, and to get to know the rank of the recording head.

Therefore, it is possible to measure the lightness of one gradationlevel, to determine which gamma correction table is used from the value,and to perform image processing using the gamma correction table.

Time which selection of the gamma correction parameter takes can beshortened overwhelmingly by this, and the time of process inspection isshortened.

Next, the discharging characteristics that the recording heads differinstead of lightness can be measured as the ink-jet printing device ofthe embodiment 3, and the gamma correction parameter can also be chosen.

Recently, as process inspection in the factory, the characteristics ofthe recording head are measured, and the rank of the recording head isattached or it sorts.

Then, the characteristics are seen and the gamma correction parameter ischosen.

As characteristics of the recording head, the ink drop velocity Vj ismeasured and the gamma correction parameter is changed according to thesize of the velocity difference with the target.

For example, since how to spread when reaching paper becomes large andthe diameter of the dot becomes large when the ink drop velocity Vj isthe quick recording head, the small gamma correction value is chosen asa gamma correction parameter.

On the contrary, when Vj is small, the larger gamma correction parameteris chosen.

Next, according to the discharging characteristics about the ink dropvolume, the example which chooses the gamma correction parameter will beexplained as the ink-jet printing device of the embodiment 4.

In the ink-jet printing device of the embodiment 4, the ink drop volumeMj is measured and the gamma correction parameter is changed accordingto the volume difference with the target ink drop volume Mj.

For example, the diameter of the dot when adhering to paper becomessmall when the ink drop volume Mj is small, and the larger gammacorrection parameter is chosen. Conversely, the diameter of the dotbecomes large when the ink drop volume Mj is large, and the smallergamma correction parameter is chosen.

Furthermore, the ink-jet printing device of the embodiment 5 will bedescribed.

The ink-jet printing device of the embodiment 1 shown in FIG. 1 is thecolor ink jet printer which used the recording head of the four colorsof Y, M, C, and K.

With this color ink jet printer, about each head, each dischargingcharacteristics are measured and the gamma correction parameter ischosen for every recording head.

What is necessary is to measure the ink drop velocity Vj and the inkdrop volume Mj as characteristics of the recording head, as mentionedabove, and just to change the gamma correction parameter.

Generally, the physical-properties value (for example, surface tensionand viscosity which influence discharging characteristics) changessomewhat with colors of the ink. If the surface tension differs fromviscosity, variation will arise in discharging characteristics.

Moreover, the profile (relation between the gradation level andlightness) of lightness also changes with colors. Therefore, even if thedifference in the physical-properties value and the difference indischarging characteristics arising from the ink arise by measuringdischarging characteristics (Vj, Mj) for every color, and choosing thegamma correction parameter according to each dischargingcharacteristics, the optimal gamma correction parameter for each recordprinting head can always be chosen.

The plurality of gamma correction parameters are beforehand stored bythe color ink jet printer or printer driver of the present invention.

The gamma correction parameter here is the table on which the outputvalue is set up to the gradation levels 0-255 as mentioned above.

When performing image processing by the ink jet printer side, it isnecessary to also memorize the plurality of gamma correction parameterswhich responded to the color in the ink jet printer, and they areusually stored by the memories, such as ROM.

Moreover, as shown in FIG. 4, when the gamma correction is performed bythe printer driver of PC, the storage apparatus, such as the hard diskin PC, memorize.

Out of the plurality of gamma correction parameters which preserved thecase where the latter printer driver performed image processing when theconcrete embodiment is described further at the example, according tothe gamma correction parameter for every color chosen for being the bestfor the recording head for every color carried, the printer driverperforms image processing to the image data of the color patch, andoutputs the image data to the ink jet printer.

In the ink jet printer side, according to the image data which received,the recording head is driven and the color patch is outputted to therecording paper.

Even if the recording head changed as shown in FIG. 11 when thelightness is measured, the profile of the almost same lightness is ableto be obtained.

Consequently, by performing image processing in the printer or printerdriver using the selected gamma correction parameter, when the ink jetprinter is created by these recording heads, even if which ink jetprinter performed image creation, the almost same image quality isobtained.

Next, the color ink jet printer of the embodiment 6 will be explained.

FIG. 12 shows the relation between the gradation level and the lightnessfor every color, and the variation thereof. As is apparent from FIG. 12,the ranges of the size and lightness variation (size of variation) fromwhich the lightness over the gradation level changes for every colordiffer.

Then, it is desirable to measure the lightness of each color and tochoose the gamma correction parameter from each lightness for everycolor.

Even if the recording head from which characteristics differ for everycolor is used because this performs image processing using the gammacorrection parameter which makes it possible to select the optimal gammacorrection parameter, and is optimized for every color of this in eachcolor, it is possible to obtain the always same image quality.

Moreover, the method of selection of the gamma correction parameter isdescribed in more detail from the result which evaluated theimage-processing method of the present invention.

With the color ink jet printer which carried the recording head of Y, M,C, and K, the recording head of Y, M, and K remained as it is, the cyanC is exchanged for the plurality of printing heads, and the color patchimage outputted using the same gamma correction parameter is compared.

The outputted color patches are the cyan C, the green G, and the colorpatch of the black B.

Consequently, when lightness exceeded the average ±10, the being cleardifference is found and it turns out that it is necessary to make itbecome less than ±five the optimal the less than ±ten averages.

Therefore, when the optimal gamma correction parameter is chosen to thevariation in the recording head, it is necessary to create the gammacorrection parameter so that the output image may fall within the rangeof the limits.

Moreover, as for the relation between the gradation level and lightness,the profile changes greatly with colors. For example, in the case of theyellow Y, to the gradation levels 0-255, although the lightnessdifference is as small as ten or less, in the case of the black K, thereis the difference very much or more with 70.

Moreover, the variation over the recording head of the yellow Y is alsosmall, and that of the black K is large. Therefore, if the kind of gammacorrection parameter is set up to the variation in lightness so that itmay become within a certain lightness difference, in the kind of number,the difference will arise in the yellow Y and the black K.

For example, dispersion between the recording heads of the lightness ofthe yellow Y is 4, the black K is 14, and if the variation in lightnessuses the one kind of gamma correction parameter to 2, the yellow Y willend with the two kinds of gamma correction parameters to the eight kindsof gamma correction parameters being required for the black K.

Therefore, according to the color, it becomes possible to change thenumber of the kinds of gamma correction parameter, and simplification ofselection and reduction of the memory or the hard disk which memorizesthe gamma correction parameter can be aimed at.

Next, the color ink jet printer of the embodiment 7 will be explained.

When measuring the lightness of the yellow Y and choosing the gammacorrection parameter of the recording head of the yellow, lightnesschange of the yellow Y is small among the gradation levels 0-255, and itis necessary to carry out very highly precise measurement as shown inFIG. 12.

Moreover, it is easy to produce the error in measurement. Therefore, theoptical density of the color patch is measured to the change whichmeasures lightness, and the gamma correction parameter is chosen as itfrom the variation in the optical density.

FIG. 13 shows the relation between the gradation level and the opticaldensity of the yellow Y, and its variation.

As shown in FIG. 13, in the case of the optical density, to thegradation level, it changes comparatively a lot and is easy todistinguish the variation between the recording heads. Therefore, theoptical density of the color patch of the yellow Y is measured and thegamma correction parameter is chosen from the optical density value.

Next, the correction method of dispersion between the heads of thedischarging characteristics in the ink jet printer of the embodiment 8will be explained.

FIG. 14 shows the relation between the gradation level and the opticaldensity in the recording head, and is the result of preparing someheads, changing the head, printing the color patch of middle the opticaldensity (gradation levels 0-255) by image processing of gamma throughand the dithering matrix, and measuring the optical density.

Change considered only as the head, and the driving conditions (drivewaveform, drive frequency), kind of recording paper, etc. are the same,and are printed.

0-254 measured measurement of the optical density every gradation level2 in the condition of the gradation levels 0, 2, and 4, . . . , 250,252, 254 and 255, and, finally the gradation level 255 is measured. TheX-Rite938 of X-Rite is used for measurement of the optical density.

As shown in FIG. 14, when the head changes, it turns out that thedifference is in the optical density obtained also on the same drivingconditions.

On the other hand, the gamma correction table is changed as shown inFIG. 10A, and the optimal gamma parameter for each head is chosen.

As a gamma correction table, although the gamma curve has width withinthe recess, FIG. 10A is not having restricted to it, and may be able tobe chosen from the recess to the projection as in FIG. 10B. These aredecided by the characteristics of the ink-jet head.

The plurality of gamma correction parameters are beforehand stored bythe ink jet printer or printer driver of the present invention.

The gamma correction parameter here is the table on which the outputvalue is set up to the gradation levels 0-255. When performing imageprocessing by the ink jet printer side, it is necessary to also memorizethe plurality of gamma correction parameters in the ink jet printer, andthey are usually stored by the memories, such as ROM.

Moreover, as shown in FIG. 6, when the gamma correction is performed bythe printer driver of PC, the storage apparatus, such as the hard diskin PC, memorize. According to the gamma correction parameter chosen fromthe plurality of gamma correction parameters which preserved the casewhere the latter printer driver performed image processing when theconcrete embodiment is described further at the example for being thebest for the ink-jet head, the printer driver performs image processingto the image data of the color patch, and outputs the image data to theink jet printer.

The selection method of the optimal gamma correction parameter will bedescribed.

Beforehand, the table is prepared for the optical density in thepredetermined gradation level, and the relation of the optimal gammacorrection parameter.

Table 1 is an example of the table and given below. Since the optimalgamma correction parameter in the optical density with various preparingthe plurality of levels as a predetermined gradation level is obtained,and the gamma correction parameter can be chosen with more sufficientaccuracy as shown in Table 1, it is desirable.

Moreover, Table 1 is each gradation level, and is the table having shownthe kind (number) of gamma correction parameter to choose, and the rangeof the optical density as which it is chosen. TABLE 1 Gamma CorrectionPara. Select. Table of Black Ink Gradation Gamma Correction ParameterNumber (kind) Level: 1 2 3 4 0.81 0.77 0.73 0.70 130 — — — — 0.77 0.730.70 0.66 0.90 0.86 0.82 0.79 150 — — — — 0.86 0.82 0.79 0.75 0.98 0.940.90 0.87 170 — — — — 0.94 0.90 0.87 0.83 Gradation Gamma CorrectionParameter Number (kind) Level: 5 6 7 8 0.66 0.63 0.59 0.55 130 — — — —0.63 0.59 0.55 0.50 0.75 0.72 0.68 0.65 150 — — — — 0.72 0.68 0.65 0.610.83 0.79 0.76 0.72 170 — — — — 0.79 0.76 0.72 0.68

The optical density of the color patch is measured for each of theplurality of actually printed gradation levels.

It is necessary to perform printing at this time by gamma through (forthe input gradation level and the output gradation level to be equal).

The gamma correction parameter in each gradation level is chosen fromthe measured optical density value and Table 1.

Let most things be the gamma correction parameters of this head by thekind of gamma correction parameter obtained on the plurality ofgradation levels.

FIG. 15 is the view which chose the optimal gamma correction parameterand in which showing the result which measured the relation between thegradation level and lightness using the different recording head.

In this way, using the selected gamma correction parameter, according tothe image data which received, the head is driven and the color patch isoutputted to the recording paper by the ink jet printer side.

Even if the head changed as shown in FIG. 15 when the optical density ismeasured, the profile of the almost same optical density is able to beobtained.

Consequently, by performing image processing in the printer or printerdriver using the selected gamma correction parameter, when the ink jetprinter is created with these heads, even if which ink jet printerperformed image creation, the almost same image quality is obtained.

Moreover, in this embodiment, since what is necessary is just to createthe image of the color patch and to carry out the color measurementwithout disassembling especially the device since the variation betweenthe heads is detected by measuring the optical density and the optimalgamma correction table is chosen, the gamma correction parameter can bechosen very easily.

Moreover, not in the head simple substance but in the state where it iscomposed as a printer, since the gamma correction parameter can bechosen therefore, it can carry out easily even in the assembly line ofthe factory, assembles, and becomes shortening of inspection time.

Moreover, it becomes possible not only the process of the factory butfor the user to carry out. As another embodiment, the example whichmeasures the optical density on one gradation level is shown.

FIG. 16 is the view in the different head showing the relation betweenthe gradation level and the optical density.

When there is the relation that the different profiles of the gradationlevels of the head and the optical density do not cross so that therelation of the gradation level and the optical density as shown in FIG.16 may show (this relation is generally realized), it is measuring thelightness of the gradation level of one somewhere, and it is possiblefor it to be decided uniquely of which profile it will be the relation,and to get to know the rank of the head.

Therefore, it is possible to measure the optical density of onegradation level, to determine which gamma correction table is used fromthe value, and to perform image processing using the gamma correctiontable.

Thereby, the time which selection of the gamma correction parametertakes may be overwhelmingly short, and the time of process inspection isshortened.

Moreover, another embodiment in the color ink jet printer will beexplained.

FIG. 17 is the diagram in which the relation and variation of thegradation level and the optical density for every color are shown.

The ranges of the size and the optical density variation (size ofvariation) from which the optical density to the gradation level changesdiffer for every color.

Then, it is desirable to measure the optical density of each color andto choose the gamma correction parameter from each the optical densityfor every color.

Namely, the color patch which created the selection table as shown inTable 1 in each optical density range, and measured it for every color.

Even if the head from which characteristics differ for every color isused by performing image processing using the gamma correction parameterwhich became possible choosing the optimal gamma correction parameter,and is optimized for every color of this in each color by comparing thetable, it is possible to obtain the same image quality invariably.

As the same image quality is obtained, when the gray and black are madefrom the three colors of Y, M, and C, it says making it the differenceof the saturation of the gray by the printer or black become ten orless.

By making the difference of saturation or less into ten, the differencein the color between the printers will not be recognized, but the almostsame color will be obtained from the experimental results.

If the selection method of the gamma correction parameter of thisembodiment is described still more concretely, the color patch of thegradation levels 0-255 will be first printed in Y, M, C, and K eachcolor with the ink jet printer.

It is necessary to use the gamma correction value when measuring therelation between the optical density and the gamma correction parameterbeforehand as a gamma correction value at this time.

In this embodiment, when it asked for the relation between the opticaldensity and the gamma correction parameter beforehand, it carried out bygamma through (the input and the output are the gamma table of therelation of 1 to 1).

Therefore, it outputted by gamma through also at the time of the outputof the color patch.

Moreover, half-tone processing used dithering. In this way, the opticaldensity of the color patch which is equivalent to the gradation level128 out of the outputted color patch as a gradation level specificationis decided to be is measured.

The optimal gamma correction parameter for this recording head is chosenfrom the relation between the measured optical density, the opticaldensity which it creates beforehand, and the gamma correction parameter.Thus, image processing is performed using the selected gamma correctionparameter.

Also to another ink jet printer, the optical density is measured by thesame method and the optimal gamma correction parameter for the ink jetprinter is chosen from the optical density.

When the color image outputted with these two ink jet printers iscompared, both are able to obtain the almost same image quality.

When both ink jet printers created and compared the image using the samegamma correction parameter for comparison, it became the image fromwhich the optical density of the image and the hue differed.

Next, the ink jet printer of the embodiment 9 will be explained.

It is the inspection process of the factory etc. and the gammacorrection parameter chosen as described above is displayed on the mainpart of the ink-jet printing device.

On the other hand, the printer driver is required in order to create theimage with this ink jet printer.

Generally, the printer driver is used, after installing in PC to whichthe ink jet printer is connected. In this way, after being installed inPC, it is necessary to the printer driver to direct the gamma correctionparameter suitable for this ink jet printer.

It becomes possible to direct the gamma correction parameter used forthe printer driver by displaying the gamma correction parameter chosenas the main part of the ink jet printer as this method as mentionedabove.

The display method to the main part of the ink jet printer has desirablenumber, sign, etc. which show the kind of for example, gamma correctionparameter.

The gamma correction table on which the optimal gamma correctionparameter for the connected ink jet printer is set up, and the outputvalue is set up to the gradation levels 0-255 in inputting this displaydata into the printer driver of PC is chosen, and it is used with theprinter driver. Moreover, you may display the gamma correction parameterused for the printer driver as an embodiment 10 on the recording headinstead of the main part of the ink jet printer.

By displaying on the recording head, when printing head exchange isperformed while the user used it, the setup of the optimal gammacorrection parameter is attained to the exchanged recording head.

Next, FIG. 18 shows the composition of the image forming system of theembodiment 11.

In the image forming system of the embodiment 11, the personal computer(PC) 35 and the ink jet printer 38 are connected through thebi-directional I/F (for example, Centronics I/F) or the network I/F 37and 39 so that the bi-directional communication is possible.

The image data after the processing is performed by the image-processingunit of the printer driver of the PC 35 or the various statusinformation of the ink jet printer 38 is bi-directionally transmittedbetween the PC and the ink jet printer through the network interfaces 37and 39.

The printer driver of the PC stores into the memory the kinds of thegamma correction parameters (or the gamma correction table itself)obtained from the ink jet printer by the bi-directional communication.Thereby, the optimal gamma correction parameter for the ink jet printerconnected to the PC can be recognized by the printer driver side, and itis possible to perform the image processing according to the optimalgamma correction parameter.

Next, the image forming system of the embodiment 12 will be explained.In this image forming system, the ink jet printer and the PC areconnected through the bi-directional I/F (for example, Centronics I/F)or network I/F so that the bi-directional communication is possible.

The image data after the various processings are performed by theimage-processing unit of the printer driver of the PC or the variousstatus information of the ink jet printer is bi-directionallytransmitted between the PC and the ink jet printer through the I/F.

The optimal gamma correction parameter for the ink jet printer is storedin the memory, for example, the ROM etc. in the ink jet printer.Moreover, the CPU and the I/F circuit of the ink jet printer are capableof transmitting to the PC through the I/F the gamma correction parameterstored in the memory upon receipt of a request from the PC.

On the other hand, the printer driver of the PC stores into the memorythe data which indicates the kind of the optimal gamma correctionparameter obtained from the ink jet printer by the bi-directionalcommunication.

The plurality of gamma correction tables in which the output levelscorresponding to the gradation levels 0-255 and related with the dataindicating kinds of the gamma correction parameters are set up arestored in the printer driver. By using the gamma correction tables, theoptimal gamma correction parameter for the ink jet printer connected tothe PC can be recognized by the printer driver side, and it is possibleto perform the image processing according to the optimal gammacorrection parameter.

Next, the thermal printing device of the embodiment 13 will beexplained.

FIG. 19 shows the mechanical part of the thermal printing device as theserial printer in which the present invention is embodied.

The thermal printing device shown in FIG. 19 is the printer of the lineprinter type using the thermal recording head 51 in which the pluralityof heating elements are arranged in line according to the width of therecording medium.

The thermal recording head 51 is formed so that it may contact with thesuitable pressure to the platen 52 countered and prepared through therecording medium.

With the paper sending roller 53 and the pressure roller 54, the thermalpaper 55 which is the recording medium is pulled out from the thermalpaper roll, and is sent between the thermal recording head 51 and theplaten 52.

If the thermal paper 55 detects having arrived at the predeterminedposition, the image signal will be sent to the thermal recording head51, each heating element will be made to generate heat according to theimage signal, and it will print to thermal paper 55.

In addition, although the example of FIG. 15 showed the example whichuses thermal paper, transfer printing can also be performed using theplain paper and the copy sheet.

As described above, having paid one's attention to the gamma parameterin the various parameters of image processing does not require cost withlast thing, because creation and the correction are easy as a parameter.

Although the same management is possible also for the CMM table in imageprocessing, the environment of exclusive use is required for CMM tablecreation, and the correction is not easy, even if it is going to adjustby the user's own hand, after there being no flexibility and crossing tothe user's hand as a product in the stage of development, since it isthe work which time and effort requires very much.

On the other hand, if it is the gamma parameter, even if it is themetaphor user level, it is possible to make creation and the correctioneasily.

Although the concrete embodiment of the present invention showed onlythe ink-jet printing device and the thermal printing device, it drivesthe printing element based on the multi-level image data.

As other examples of the recording head of the printing device whichforms the image on the recording medium Along with the photoconductordrum in the electrophotographic printer, the high-density light emittingdiode array recording head is configured.

The recording head of the light emitting diode printer which this ismade to be focused on the photoconductor drum using the convergent rodarray lens.

The present invention can also be applied to the recording head of theliquid crystal printer performed by controlling electrically thetransmission quantity of light of the liquid crystal of a large numberwhich arranged optical beam irradiation to the photoconductor drum inthe shape of an array etc., and all are the things of technical withinthe limits of the present invention.

According to the present invention, the following effects are done sothat clearly from the above explanation. It has the recording head inwhich the plurality of printing elements like the ink-jet recording headand the thermal recording head are formed, and in the image-processingmethod of the printing device which drives the printing element based onthe multi-level image data, and forms the image on the recording medium,even if variation is in the characteristics of the recording head,variation can be corrected only by choosing the gamma correctionparameter according to characteristics, without changing the drivingconditions of the recording head etc.

Moreover, even if it can correct variation and performs the imageformation by which printing device, without changing the drivingconditions of the recording head etc. by producing and carrying out theside color of the color patch, and choosing the gamma correctionparameter by the recording head, even if variation is in the lightnessand the optical density of the printed image, the same image quality isobtained.

Moreover, even if variation is in discharging characteristics in thecase of the ink-jet recording head, while being able to correctvariation easily, and not generating the satellite dot, the dust, etc.in the formed image but obtaining desirable image quality by choosingthe gamma correction parameter according to discharging characteristics,without changing the driving conditions of the ink-jet recording headetc., even if it performs the image formation by which ink-jet printingdevice, the same image quality is obtained.

Furthermore, since in the case of the color ink-jet printing device theoptimal gamma correction parameter is chosen for every ink-jet recordinghead of each color and the image formation is performed, even if itperforms the image formation by which ink-jet printing device, theoptical density of the formed image and the hue are not different andhigh image quality is obtained.

In addition, although this embodiment showed the example lightness ismade to become ±ten or less, making not lightness but saturation of theblack of the YMC colors below into the predetermined value also has thesame effect from the point of obtaining the higher image quality fromwhich the hue is not different to the black made from the YMC colors.

By the human eyes, the black which does not have dispersion in the hueis obtained by considering as ±ten or less saturation from theexperiment of present-invention persons also as a predetermined value inthis case.

The present invention is not limited to the above-described embodimentsand variations and modifications may be made without departing from thescope of the invention. For example, the image forming apparatus towhich the present invention is applied may be various kinds of imageforming devices, such as printer, copier, and facsimile.

1. An image-processing method for a printing device which has arecording head in which a plurality of printing elements are providedand drives the printing elements based on multi-level image data to forman image on an recording medium, comprising the steps of: selecting agamma correction parameter according to printing characteristics of therecording head; and forming an image on the recording medium based onthe selected gamma correction parameter.
 2. A printing device which hasa recording head in which a plurality of printing elements are providedand drives the printing elements based on multi-level image data to forman image on an recording medium, comprising: a selection unit selectinga gamma correction parameter according to printing characteristics ofthe recording head; and an image forming unit forming an image on therecording medium based on the gamma correction parameter selected by theselection unit.
 3. An image-processing method for a printing devicewhich has a recording head in which a plurality of printing elements areprovided and drives the printing elements based on multi-level imagedata to form an image on an recording medium, comprising the steps of:selecting a gamma correction parameter according to lightnesscharacteristics of a printed image of the recording head; and forming animage on the recording medium based on the selected gamma correctionparameter.
 4. A printing device which has a recording head in which aplurality of printing elements are provided and drives the printingelements based on multi-level image data to form an image on anrecording medium, comprising: a selection unit selecting a gammacorrection parameter according to lightness characteristics of a printedimage of the recording head; and an image forming unit forming an imageon the recording medium based on the gamma correction parameter selectedby the selection unit.
 5. An image-processing method for a printingdevice which has a recording head in which a plurality of printingelements are provided and drives the printing elements based onmulti-level image data to form an image on an recording medium,comprising the steps of: selecting a gamma correction parameteraccording to optical density characteristics of a printed image of therecording head; and forming an image on the recording medium based onthe selected gamma correction parameter.
 6. A printing device which hasa recording head in which a plurality of printing elements are providedand drives the printing elements based on multi-level image data to forman image on an recording medium, comprising: a selection unit selectinga gamma correction parameter according to optical densitycharacteristics of a printed image of the recording head; and an imageforming unit forming an image on the recording medium based on the gammacorrection parameter selected by the selection unit.
 7. Animage-processing method for an ink-jet printing device which has anink-jet recording head in which a plurality of nozzles are provided anddischarges ink drops from the plurality of nozzles based on multi-levelimage data to form an image on an recording medium, comprising the stepsof: selecting a gamma correction parameter according to dischargingcharacteristics of the ink-jet recording head; and forming an image onthe recording medium based on the selected gamma correction parameter.8. An ink-jet printing device which has an ink-jet recording head inwhich a plurality of nozzles are provided and discharges ink drops fromthe plurality of nozzles based on multi-level image data to form animage on an recording medium, comprising: a selection unit selecting agamma correction parameter according to discharging characteristics ofthe ink-jet recording head; and an image forming unit forming an imageon the recording medium based on the gamma correction parameter selectedby the selection unit.
 9. The ink-jet printing device according to claim8 wherein the discharging characteristics of the ink-jet recording headare characteristics of an ink drop volume to an input gradation level.10. The ink-jet printing device according to claim 8 wherein thedischarging characteristics of the ink-jet recording head arecharacteristics of an ink drop velocity to an input gradation level. 11.An image-processing method for an ink-jet printing device which has anink-jet recording head in which a plurality of nozzles are provided anddischarges ink drops from the plurality of nozzles based on multi-levelimage data to form an image on an recording medium, comprising the stepsof: selecting a gamma correction parameter according to lightness of aprinted image of the ink-jet recording head; and forming an image on therecording medium based on the selected gamma correction parameter. 12.An ink-jet printing device which has an ink-jet recording head in whicha plurality of nozzles are provided and discharges ink drops from theplurality of nozzles based on multi-level image data to form an image onan recording medium, comprising: a selection unit selecting a gammacorrection parameter according to lightness of a printed image of theink-jet recording head; and an image forming unit forming an image onthe recording medium based on the gamma correction parameter selected bythe selection unit.
 13. The ink-jet printing device according to claim12 wherein the gamma correction parameter is selected according to thelightness of the printed image to a plurality of gradation levels. 14.The ink-jet printing device according to claim 12 wherein the gammacorrection parameter is selected according to the lightness of theprinted image to one gradation level.
 15. An image-processing method foran ink-jet printing device which has an ink-jet recording head in whicha plurality of nozzles are provided and discharges ink drops from theplurality of nozzles based on multi-level image data to form an image onan recording medium, comprising the steps of: selecting a gammacorrection parameter according to an optical density of a printed imageof the ink-jet recording head; and forming an image on the recordingmedium based on the selected gamma correction parameter.
 16. An ink-jetprinting device which has an ink-jet recording head in which a pluralityof nozzles are provided and discharges ink drops from the plurality ofnozzles based on multi-level image data to form an image on an recordingmedium, comprising: a selection unit selecting a gamma correctionparameter according to an optical density of a printed image of theink-jet recording head; and an image forming unit an image on therecording medium based on the gamma correction parameter selected by theselection unit.
 17. The ink-jet printing device according to claim 16wherein the gamma correction parameter is selected according to theoptical density of the printed image to a plurality of gradation levels.18. The ink-jet printing device according to claim 16 wherein the gammacorrection parameter is selected according to the optical density of theprinted image to one gradation level.
 19. An ink-jet printing devicewhich has a plurality of ink-jet recording heads in which a plurality ofnozzles are provided for each ink-jet recording head and discharges inkdrops of a plurality of colors from the plurality of nozzles of theplurality of ink-jet recording heads respectively based on multi-levelimage data to form a color image on an recording medium, each ink-jetrecording head comprising: a selection unit selecting a gamma correctionparameter of a corresponding color according to dischargingcharacteristics of the ink-jet recording head.
 20. An ink-jet printingdevice which has a plurality of ink-jet recording heads in which aplurality of nozzles are provided for each ink-jet recording head anddischarges ink drops of a plurality of colors from the plurality ofnozzles of the plurality of ink-jet recording heads respectively basedon multi-level image data to form a color image on an recording medium,each ink-jet recording head comprising: a selection unit selecting agamma correction parameter of a corresponding color according tolightness of the corresponding color of a printed image of the ink-jetrecording head.
 21. An ink-jet printing device which has a plurality ofink-jet recording heads in which a plurality of nozzles are provided foreach ink-jet recording head and discharges ink drops of a plurality ofcolors from the plurality of nozzles of the plurality of ink-jetrecording heads respectively based on multi-level image data to form acolor image on an recording medium, each ink-jet recording headcomprising: a selection unit selecting a gamma correction parameter of acorresponding color according to an optical density of the correspondingcolor of a printed image of the ink-jet recording head.
 22. The ink-jetprinting device according to any of claims 8, 16 and 19-21 wherein theselected gamma correction parameter is displayed.
 23. The ink-jetprinting device according to any of claims 19-21 wherein the selectedgamma correction parameters of the plurality of colors are displayedrespectively.
 24. A printer driver of an ink-jet printing device whichcarries out the image-processing method according to any of claims 7, 11and 15 wherein the image data is outputted to the ink-jet printingdevice according to the selected gamma correction parameter.
 25. Theprinter driver according to claim 24 wherein the printer drivercomprises a unit setting the selected gamma correction parameter to theink-jet printing device.
 26. An image processing apparatus whichcommunicates with an ink-jet printing device, comprising: a requestingunit requesting a gamma correction parameter or a kind thereof to. theink-jet printing device; a receiving unit receiving the gamma correctionparameter or the kind thereof from the ink-jet printing device; and animage processing unit adjusting a gamma correction parameter based onthe gamma correction parameter or the kind thereof received by thereceiving unit.
 27. The ink-jet printing device according to any ofclaims 8, 12, 16 and 19-21 wherein the ink-jet printing device comprisesa unit storing a plurality of gamma correction parameters, and one ofthe plurality of the gamma correction parameters is selected.
 28. Theink-jet printing device according to any of claims 19-21 wherein theink-jet printing device comprises a unit storing a plurality of gammacorrection parameters of the plurality of colors, and one of theplurality of the gamma correction parameters is selected.
 29. Theink-jet printing device according to any of claims 19-21 wherein thegamma correction parameters are selected such that a difference inlightness between different printed images of the plurality of ink-jetrecording heads for a same color is less than ±10.
 30. The ink-jetprinting device according to any of claims 19-21 wherein the ink-jetprinting device comprises a unit storing the selected gamma correctionparameters for the respective colors, and values of the selected gammacorrection parameters for at least two colors are different.
 31. Theink-jet printing device according to claim 30 wherein the ink-jetprinting device comprises a unit setting a kind of the selected gammacorrection parameter of each ink-jet recording head to the ink-jetprinting device.
 32. An image forming system including an imageprocessing apparatus and an ink-jet printing device, the imageprocessing apparatus comprising: a requesting unit requesting a gammacorrection parameter selection data to the ink-jet printing device; areceiving unit receiving the gamma correction parameter selection datafrom the ink-jet printing device; and an image processing unit selectingone of a plurality of gamma correction parameters based on the gammacorrection parameter selection data received by the receiving unit, andthe ink-jet printing device comprising: a storing unit storing the gammacorrection parameter selection data; and a transmitting unittransmitting the gamma correction parameter selection data to the imageprocessing apparatus.
 33. An image forming method of an image formingsystem including an image processing apparatus and an ink-jet printingdevice, the image forming method comprising the steps of: requesting agamma correction parameter selection data to the ink-jet printing devicefrom the image processing apparatus; creating the gamma correctionparameter selection data by the ink-jet printing device; transmittingthe created the gamma correction parameter selection data to the imageprocessing apparatus; receiving the gamma correction parameter selectiondata from the ink-jet printing device by the image processing apparatus;and selecting a gamma correction parameter based on the received gammacorrection parameter selection data.
 34. The image-processing methodaccording to claim 1 or 3 wherein the recording head in which theplurality of printing elements are provided is a thermal recording head,the gamma correction parameter is selected according to gradationprinting characteristics of the thermal recording head, and the image isformed on the recording medium based on the selected gamma correctionparameter.
 35. The printing device according to claim 2 or 4 wherein therecording head in which the plurality of the printing elements areprovided is a thermal recording head, the selection unit selects thegamma correction parameter according to gradation printingcharacteristics of the thermal recording head, and the image formingunit forms the image on the recording medium based on the gammacorrection parameter selected by the selection unit.